The document EP 0727249 discloses a static mixer for the mixing of highly viscous media. The static mixer includes a tube and also a mixer insert arranged within the tube. The mixer insert is also termed a mixing element. A disadvantage of this mixer is the fact that the manufacture of the mixer insert is very complicated and thus costly. A disadvantage is moreover the fact that the mixer insert has ribs at its periphery extending in the longitudinal direction to the tube wall which serve to reinforce the mixer in the axial direction against the pressure drop forces which likewise occur in the axial direction along which a medium to be mixed can flow in the axial direction unhindered through the boundary regions in which the longitudinal ribs extend which considerably reduces the mixing quality of the mixer.